It is becoming clear that periodontitis is not only characterized by pathogenic infection, but even more so by a loss of immunological homeostasis. Strategies toward resolution of regenerating the periodontium without completely blocking immune responses against local and systemic infections would be ideal. Our long-term objective is to address the physiological cause of periodontitis through an understanding of the inflammatory and regulatory processes of the periodontium. Correspondingly, recent data in our laboratories indicate that periodontitis symptoms are accompanied by the absence of an important cell subset called regulatory T-cells. We hypothesize that controlled release formulations of Treg-recruiting factors is a viable way to regenerate the periodontal space. This hypothesis is supported by our preliminary data demonstrating that controlled release of Treg recruiting factors leads to an increase in regulatory T-cells in the periodontium, in the draining lymph nodes, and, consequently, resolution of periodontal disease symptoms 2 mouse models. Specific Aim I: To engineer controlled release formulations that can influence the number of Tregs in the periodontium and abrogation of the symptoms of periodontitis. We will rationally design and fabricate controlled release microparticles to produce various release profiles of Treg recruiting factors and then examine their effect on alveolar bone loss using two different murine models of periodontal disease. Furthermore, we will explore the expansion of local lymphocytes toward an enriched population of Tregs through controlled release of a combination of several key molecules. Specific Aim II: To better understand the biological mechanisms of Treg recruitment and function in periodontal tissues. We will examine the mechanisms of Treg chemotaxis in the periodontium by monitoring gene expression in response to Treg recruiting therapies and chemotaxis in mice deficient in receptors thought to be important for migration and function of Tregs. We will then investigate the duration of Treg residence in the periodontium under inflammatory conditions after a single injection of our preliminary CCL22 microparticle formulations. We will also examine the expression levels of molecular markers associated with Tregs and tissue metabolism to elucidate the mechanisms of Treg-mediated periodontal disease abrogation. PUBLIC HEALTH RELEVANCE: This work has relevance to public health as it intends to address the most pressing oral health concern today, affecting over 78 million Americans. This disease affects not only tooth loss, but also the incidence of cardiovascular disease, diabetes, respiratory diseases, and even premature childbirth. Furthermore, our approach may also have relevance to other diseases such as osteoarthritis of the temporo-mandibular joint.